/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.engine.load;

import org.apache.iotdb.common.rpc.thrift.TTimePartitionSlot;
import org.apache.iotdb.commons.concurrent.IoTDBThreadPoolFactory;
import org.apache.iotdb.commons.conf.IoTDBConstant;
import org.apache.iotdb.commons.file.SystemFileFactory;
import org.apache.iotdb.commons.utils.FileUtils;
import org.apache.iotdb.db.conf.IoTDBConfig;
import org.apache.iotdb.db.conf.IoTDBDescriptor;
import org.apache.iotdb.db.engine.storagegroup.DataRegion;
import org.apache.iotdb.db.engine.storagegroup.TsFileResource;
import org.apache.iotdb.db.exception.LoadFileException;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.load.LoadTsFilePieceNode;
import org.apache.iotdb.db.mpp.plan.scheduler.load.LoadTsFileScheduler;
import org.apache.iotdb.db.mpp.plan.scheduler.load.LoadTsFileScheduler.LoadCommand;
import org.apache.iotdb.db.utils.FileLoaderUtils;
import org.apache.iotdb.tsfile.common.constant.TsFileConstant;
import org.apache.iotdb.tsfile.exception.write.PageException;
import org.apache.iotdb.tsfile.write.writer.TsFileIOWriter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

/**
 * {@link LoadTsFileManager} is used for dealing with {@link LoadTsFilePieceNode} and {@link
 * LoadCommand}. This class turn the content of a piece of loading TsFile into a new TsFile. When
 * DataNode finish transfer pieces, this class will flush all TsFile and laod them into IoTDB, or
 * delete all.
 */
public class LoadTsFileManager {
    private static final Logger logger = LoggerFactory.getLogger(LoadTsFileManager.class);
    private static final IoTDBConfig config = IoTDBDescriptor.getInstance().getConfig();

    private final File loadDir;

    private final Map<String, TsFileWriterManager> uuid2WriterManager;

    private final ScheduledExecutorService cleanupExecutors;
    private final Map<String, ScheduledFuture<?>> uuid2Future;

    public LoadTsFileManager() {
        this.loadDir = SystemFileFactory.INSTANCE.getFile(config.getLoadTsFileDir());
        this.uuid2WriterManager = new ConcurrentHashMap<>();
        this.cleanupExecutors =
                IoTDBThreadPoolFactory.newScheduledThreadPool(0, LoadTsFileManager.class.getName());
        this.uuid2Future = new ConcurrentHashMap<>();

        recover();
    }

    private void recover() {
        if (!loadDir.exists()) {
            return;
        }

        for (File taskDir : loadDir.listFiles()) {
            String uuid = taskDir.getName();
            TsFileWriterManager writerManager = new TsFileWriterManager(taskDir);

            uuid2WriterManager.put(uuid, writerManager);
            writerManager.close();
            uuid2Future.put(
                    uuid,
                    cleanupExecutors.schedule(
                            () -> forceCloseWriterManager(uuid),
                            LoadTsFileScheduler.LOAD_TASK_MAX_TIME_IN_SECOND,
                            TimeUnit.SECONDS));
        }
    }

    public void writeToDataRegion(DataRegion dataRegion, LoadTsFilePieceNode pieceNode, String uuid)
            throws PageException, IOException {
        if (!uuid2WriterManager.containsKey(uuid)) {
            uuid2Future.put(
                    uuid,
                    cleanupExecutors.schedule(
                            () -> forceCloseWriterManager(uuid),
                            LoadTsFileScheduler.LOAD_TASK_MAX_TIME_IN_SECOND,
                            TimeUnit.SECONDS));
        }
        TsFileWriterManager writerManager =
                uuid2WriterManager.computeIfAbsent(
                        uuid, o -> new TsFileWriterManager(SystemFileFactory.INSTANCE.getFile(loadDir, uuid)));
        for (TsFileData tsFileData : pieceNode.getAllTsFileData()) {
            if (!tsFileData.isModification()) {
                ChunkData chunkData = (ChunkData) tsFileData;
                writerManager.write(
                        new DataPartitionInfo(dataRegion, chunkData.getTimePartitionSlot()), chunkData);
            } else {
                writerManager.writeDeletion(tsFileData);
            }
        }
    }

    public boolean loadAll(String uuid) throws IOException, LoadFileException {
        if (!uuid2WriterManager.containsKey(uuid)) {
            return false;
        }
        uuid2WriterManager.get(uuid).loadAll();
        clean(uuid);
        return true;
    }

    public boolean deleteAll(String uuid) throws IOException {
        if (!uuid2WriterManager.containsKey(uuid)) {
            return false;
        }
        clean(uuid);
        return true;
    }

    private void clean(String uuid) {
        uuid2WriterManager.get(uuid).close();
        uuid2WriterManager.remove(uuid);
        uuid2Future.get(uuid).cancel(true);
        uuid2Future.remove(uuid);

        if (loadDir.delete()) { // this method will check if there sub-dir in this dir.
            logger.info(String.format("Delete load dir %s.", loadDir.getPath()));
        }
    }

    private void forceCloseWriterManager(String uuid) {
        uuid2WriterManager.get(uuid).close();
        uuid2WriterManager.remove(uuid);
        uuid2Future.remove(uuid);

        if (loadDir.delete()) { // this method will check if there sub-dir in this dir.
            logger.info(String.format("Delete load dir %s.", loadDir.getPath()));
        }
    }

    private class TsFileWriterManager {
        private final File taskDir;
        private Map<DataPartitionInfo, TsFileIOWriter> dataPartition2Writer;
        private Map<DataPartitionInfo, String> dataPartition2LastDevice;
        private boolean isClosed;

        private TsFileWriterManager(File taskDir) {
            this.taskDir = taskDir;
            this.dataPartition2Writer = new HashMap<>();
            this.dataPartition2LastDevice = new HashMap<>();
            this.isClosed = false;

            clearDir(taskDir);
        }

        private void clearDir(File dir) {
            if (dir.exists()) {
                FileUtils.deleteDirectory(dir);
            }
            if (dir.mkdirs()) {
                logger.info(String.format("Load TsFile dir %s is created.", dir.getPath()));
            }
        }

        private void write(DataPartitionInfo partitionInfo, ChunkData chunkData) throws IOException {
            if (isClosed) {
                throw new IOException(String.format("%s TsFileWriterManager has been closed.", taskDir));
            }
            if (!dataPartition2Writer.containsKey(partitionInfo)) {
                File newTsFile =
                        SystemFileFactory.INSTANCE.getFile(
                                taskDir, partitionInfo.toString() + TsFileConstant.TSFILE_SUFFIX);
                if (!newTsFile.createNewFile()) {
                    logger.error(String.format("Can not create TsFile %s for writing.", newTsFile.getPath()));
                    return;
                }

                dataPartition2Writer.put(partitionInfo, new TsFileIOWriter(newTsFile));
            }
            TsFileIOWriter writer = dataPartition2Writer.get(partitionInfo);
            if (!chunkData.getDevice().equals(dataPartition2LastDevice.getOrDefault(partitionInfo, ""))) {
                if (dataPartition2LastDevice.containsKey(partitionInfo)) {
                    writer.endChunkGroup();
                }
                writer.startChunkGroup(chunkData.getDevice());
                dataPartition2LastDevice.put(partitionInfo, chunkData.getDevice());
            }
            chunkData.writeToFileWriter(writer);
        }

        private void writeDeletion(TsFileData deletionData) throws IOException {
            if (isClosed) {
                throw new IOException(String.format("%s TsFileWriterManager has been closed.", taskDir));
            }
            for (Map.Entry<DataPartitionInfo, TsFileIOWriter> entry : dataPartition2Writer.entrySet()) {
                deletionData.writeToFileWriter(entry.getValue());
            }
        }

        private void loadAll() throws IOException, LoadFileException {
            if (isClosed) {
                throw new IOException(String.format("%s TsFileWriterManager has been closed.", taskDir));
            }
            for (Map.Entry<DataPartitionInfo, TsFileIOWriter> entry : dataPartition2Writer.entrySet()) {
                TsFileIOWriter writer = entry.getValue();
                if (writer.isWritingChunkGroup()) {
                    writer.endChunkGroup();
                }
                writer.endFile();
                entry.getKey().getDataRegion().loadNewTsFile(generateResource(writer), true);
            }
        }

        private TsFileResource generateResource(TsFileIOWriter writer) throws IOException {
            TsFileResource tsFileResource = FileLoaderUtils.generateTsFileResource(writer);
            tsFileResource.serialize();
            return tsFileResource;
        }

        private void close() {
            if (isClosed) {
                return;
            }
            if (dataPartition2Writer != null) {
                for (Map.Entry<DataPartitionInfo, TsFileIOWriter> entry : dataPartition2Writer.entrySet()) {
                    try {
                        TsFileIOWriter writer = entry.getValue();
                        if (writer.canWrite()) {
                            writer.close();
                        }
                        if (writer.getFile().exists() && !writer.getFile().delete()) {
                            logger.warn(String.format("Delete File %s error.", writer.getFile()));
                        }
                    } catch (IOException e) {
                        logger.warn(
                                String.format(
                                        "Close TsFileIOWriter %s error.", entry.getValue().getFile().getPath()),
                                e);
                    }
                }
            }
            if (!taskDir.delete()) {
                logger.warn(String.format("Can not delete load dir %s.", taskDir.getPath()));
            }
            dataPartition2Writer = null;
            dataPartition2LastDevice = null;
            isClosed = true;
        }
    }

    private class DataPartitionInfo {
        private final DataRegion dataRegion;
        private final TTimePartitionSlot timePartitionSlot;

        private DataPartitionInfo(DataRegion dataRegion, TTimePartitionSlot timePartitionSlot) {
            this.dataRegion = dataRegion;
            this.timePartitionSlot = timePartitionSlot;
        }

        public DataRegion getDataRegion() {
            return dataRegion;
        }

        public TTimePartitionSlot getTimePartitionSlot() {
            return timePartitionSlot;
        }

        @Override
        public String toString() {
            return String.join(
                    IoTDBConstant.FILE_NAME_SEPARATOR,
                    dataRegion.getDatabaseName(),
                    dataRegion.getDataRegionId(),
                    Long.toString(timePartitionSlot.getStartTime()));
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            DataPartitionInfo that = (DataPartitionInfo) o;
            return Objects.equals(dataRegion, that.dataRegion)
                    && timePartitionSlot.getStartTime() == that.timePartitionSlot.getStartTime();
        }

        @Override
        public int hashCode() {
            return Objects.hash(dataRegion, timePartitionSlot.getStartTime());
        }
    }
}
